Embodiments relate to a light emitting device, a light emitting device package, and a lighting system.
A light emitting device (LED) may be implemented by a p-n junction diode, which has the characteristic converting an electrical energy to a light energy, and may be formed by combining a Group III element and a Group V element of the periodic table. The LED may implement various colors by adjusting the composition ratio of a compound semiconductor.
Meanwhile, according to a related art, during an electrostatic discharge (ESD), current flows in a reverse direction, so that an active layer that is a light emitting region may be damaged.
To solve the damage problem of the LED due to the ESD, a Zener diode is connected in parallel to the LED in a reverse direction to the LED and is then mounted in a package type. Therefore, in a forward bias, current flows to the LED, so that light is emitted from the LED. In an electrostatic discharge, current flows to the Zener diode, thereby capable of preventing the LED from being damaged.
However, in a related art, since the Zener diode is mounted in a package, absorption amount of light may be decreased.
Also, in a related art vertical type LED, an n-type electrode and a p-type electrode are formed at an upper portion and a lower portion of the vertical type LED, respectively for current injection.
At this time, electrons and holes respectively injected by the n-type electrode and the p-type electrode flow into an active layer and are recombined to thus generate light. The generated light is emitted to an outside, or is absorbed into or reflected by the n-type electrode, and thus is lost inside the LED. That is, according to the related art, light emitted from a layer below the n-type electrode is absorbed into or reflected by the n-type electrode, and thus light emitting efficiency may decrease. Also, according to the related art, reabsorption of light reflected by the n-type electrode may cause generation of heat.
Further, according to the related art, the lifetime and reliability of the LED may be lowered due to current crowding.